This feature is available to Subscribers Only

Context: Depression and low back problems are common issues in primary care.

Objective: To compare 6-month depression outcomes (specifically, clinical results and number of outpatient visits) in patients with or without comorbid low back conditions (LBCs). The authors hypothesized that the presence of an LBC within 3 months of the diagnosis of depression would negatively affect clinical outcomes of depression treatment after 6 months.

Design: Retrospective record review.

Setting: Collaborative care management program in a large primary care practice.

Participants: Patients with a diagnosis of depression enrolled in collaborative care management (N=1326), including 172 with and 1154 without evidence of an LBC within 3 months of enrollment.

Main Outcome Measures: Clinical depression outcomes (remission and persistent depressive symptoms) and number of outpatient visits at 6 months.

Conclusion: Increased odds of persistent depressive symptoms and increased number of outpatient visits were found in patients with depression and concomitant LBCs 6 months after enrollment into collaborative care management, compared with those in patients with depression and without LBCs. The data suggest that temporally related LBCs could lead to worse outcomes in primary care patients being treated for depression, encouraging closer observation and possible therapeutic changes in this cohort.

Depression is one of the leading reasons for primary care visits in the United States.1 Its prevalence is estimated to be 5.4% to 8.9% among the general population in the United States2,3 and 5% to 13% among primary care patients.4,5 Patients with depression tend to have somatic complaints, and for some these may be the only presenting symptoms6,7; common somatic complaints in depression include abdominal pain, back pain, fatigue, and headache.3 A global ranking of disability life-years in 2010 demonstrated low back pain as the sixth most common cause of disability and major depression disorder as the 11th.8 These are substantial increases since the prior evaluation performed in 1990, when low back pain and major depression disorder were ranked 11th and 15th, respectively.

Many patients with depression also have chronic illnesses, such as diabetes mellitus, hypertension, heart disease, and arthritis, and many studies9-11 have examined the effects of depression on outcomes of chronic conditions. Outcomes are generally poorer when patients with chronic medical conditions also have depression.5 Given the apparent bidirectional relationship between depression and comorbid medical conditions, improved outcomes have been demonstrated when management was targeted at both diseases.12-15 Pain has also been shown to be common in primary care patients with depression,16 and early management of pain is associated with improved depression outcomes.17,18

Low back pain is an extremely common clinical entity, estimated to be the fifth most common reason for all physician visits in the United States.19 Acute low back pain usually lasts a few days to weeks, whereas chronic low back pain is defined as lasting longer than 3 months.20 Depression is a known complicating factor for the latter. A 2011 study7 from Japan found that of 1426 individuals with chronic low back pain, 371 (26%) had a history of depression; other factors associated with increased risk of depression included female sex, medical aid benefits, lower educational level, and lower family income. A recent study21 analyzing 202 adult patients with chronic low back pain demonstrated a rate of current depressive symptoms as high as 22%, as well as a significant correlation between depression and somatic dysfunction scoring (P<.01).

Collaborative care management (CCM) was demonstrated to be effective for depression treatment by Unutzer et al22 in 2002 with a randomized control study of 1801 patients in the Improving Mood-Promoting Access to Collaborative Treatment (IMPACT) study. Since then, 2 meta-analyses23,24 have shown that CCM is more clinically effective than usual care only. Components of CCM include depression registry, care managers who interface with primary care and mental health professionals, therapeutic management based on clinical guidelines with evidence-based care, and oversight by a reviewing psychiatrist, usually weekly.

Prior studies of patients enrolled into CCM for treatment of their depression have shown that clinical outcomes, such as remission and persistent depressive symptoms after 6 months, are correlated with baseline depression severity, anxiety, clinical diagnosis, and abnormal results of screening for bipolar disorder.25-27 No studies to date, to our knowledge, have specifically looked at the effects of comorbid low back conditions (LBCs) on the outcomes of depression. Our aim was to compare 6-month depression outcomes (specifically, clinical results and number of outpatient visits) in patients with or without comorbid LBCs. We hypothesized that the presence of an LBC at diagnosis of depression would negatively affect clinical outcomes of depression treatment after 6 months.

Methods

In a retrospective review, we analyzed records of patients in a large multisite primary care practice who were enrolled into CCM for depression treatment from March, 1, 2008, through June 30, 2011. The CCM program was originally started at a single clinical site and by 2010 was implemented at all 5 sites within our practice of approximately 100,000 adult patients. Approximately 50% of patients were covered by the institutional health insurance plan as employees or dependents. Details on the CCM process and its implementation have been published elsewhere.27,28 To be enrolled in the CCM program, patients had to have a clinical diagnosis of major depression or dysthymia and a Patient Health Questionnaire (PHQ-9)29 score of at least 10; patients were excluded if they had a psychiatric diagnosis of bipolar disorder. A total of 1326 patients were enrolled during the time frame of the study and had complete intake data sets, with 6-month PHQ-9 follow-up data. These patients made up our study group.

The dependent variables in our analysis were clinical remission (defined as a PHQ-9 score of <5 at 6 months) or evidence of persistent depressive symptoms (PHQ-9 score of ≥10 at 6 months) and number of outpatient visits. The demographic predictor variables included age, sex, race, and marital status, and the independent clinical variables included diagnosis (first or recurrent episode of major depression or dysthymia), intake PHQ-9 score (range, 0-27), Alcohol Use Disorders Identification Test (AUDIT)30 score (range, 0-40), Generalized Anxiety Disorder 7 screen31 score (range, 0-21), Mood Disorder Questionnaire (MDQ)32 score for bipolar disorder, presence of an LBC (yes or no), and number of outpatient visits. (A “negative” MDQ screen result was defined as fewer than 7 items checked on question 1 and negative responses to questions 2 and 3; all other results were recorded as “abnormal MDQ.”) The presence of LBCs was determined by review of the electronic medical record (EMR) for a low back–related diagnosis (eg, acute, mechanical, or chronic low back pain; sciatica), evidence of lumbar radiographic testing (of any type), or physical therapy for an LBC. The review for LBCs extended from 3 months before enrollment into CCM through 3 months after enrollment.

The number of outpatient visits was determined by reviewing the EMR for outpatient clinical visits during the 6 months after enrollment into CCM; these included all provider visits within the outpatient clinic (primary, secondary, and tertiary care) and retail medicine sites and excluded any emergency room visits or hospitalizations. Patients were enrolled into our CCM program from a large multisite primary care practice sharing an EMR. To control for individual patient characteristics, we determined the total number of outpatient clinical visits for the 6 months before enrollment, as we have done for other studies in our primary care population.32-38 We also controlled for the potential for clinical site-to-site variability in outcomes by including a site location variable in the regression modeling.

Statistical analysis was performed with MedCalc software (version 12.3.0.0). We used Mann-Whitney tests for independent variables to evaluate continuous variables (because of not-normal distributions), and χ2 analysis for categorical variables. We performed regression modeling with independent variables while controlling for site-to-site differences in clinical outcomes. Outlier status for outpatient visits was defined as being in the 80th percentile or higher for outpatient visits during the 6 months after enrollment in CCM. Statistical significance was defined as P<.05. The study was reviewed and approved by Mayo Clinic's institutional review board.

Results

Of the 1326 patients studied, 172 (13.0%) met the criteria for a concomitant LBC (LBC group). Patients with LBCs were more likely to be older than those without LBCs (mean age, 45.4 vs 42.0 years; P=.03), have higher anxiety scores (mean Generalized Anxiety Disorder 7 screen score, 12.1 vs 11.1; P=.02), and have more outpatient visits before (mean, 5.5 vs 2.5 visits; P<.001) and after (7.7 vs 5.1 visits; P<.001) enrollment. For all other variables, differences were not statistically significant at univariate analysis (Table 1).

Table 1.

Comparison by Variable in 1326 Primary Care Patients With Depression Enrolled in Collaborative Care Management, With or Without Concomitant Low Back Conditions

Variable, No. (%)a

Concomitant Low Back Condition (n=172)

No Recent Back Conditions (n=1154)

P Value

Age, mean (range), y

45.4 (18.1-92.3)

42.0 (18.0-91.0)

.03

Sex, female

128 (74.4)

823 (71.3)

.45

Marital Status, married

94 (54.7)

659 (57.1)

.60

Race, white

158 (91.9)

1093 (94.7)

.18

Depression Diagnosis

.17

First episode

92 (53.5)

587 (50.9)

Recurrent

75 (43.6)

491 (42.5)

Dysthymia

5 (2.9)

76 (6.6)

Initial Scores, mean

PHQ-9

15.8

15.5

.39

GAD-7

12.1

11.1

.02

AUDIT

3.3

3.0

.60

Abnormal MDQ Score

20 (11.6)

103 (8.9)

.32

Remissionb

83 (48.3)

631 (54.7)

.14

Persistent Depressive Symptomsc

51 (29.7)

245 (21.2)

.02

Outpatient Visits, mean (range)

6 mo before enrollment

5.5 (0-22)

2.5 (0-28)

<.001

6 mo after enrollment

7.7 (1-24)

5.1 (0-35)

<.001

a Data presented as No. (%) unless otherwise indicated.

b Remission was defined as a Patient Health Questionnaire (PHQ-9) score of <5 at 6 months after enrollment.

c Persistent depressive symptoms were defined as a PHQ-9 score of ≥10 at 6 months after enrollment.

Odds Ratio for Clinical Outcomes of Depression at 6 Months After Enrollment in Collaborative Care Management, by Variable (N=1326)

Depression Outcome at 6 moa

Remission

Persistent Depressive Symptoms

Variable

Odds Ratio (CI)

P Value

Odds Ratio (CI)

P Value

Depression Diagnosis

First Episode

Referent

Referent

Recurrent

0.667 (0.525-0.847)

.001

1.227 (0.918-1.640)

.17

Dysthymia

0.992 (0.602-1.636)

.98

1.355 (0.764-2.403)

.30

Initial Test Score

PHQ-9

0.940 (0.911-0.970)

<.001

1.101 (1.062-1.142)

<.001

GAD-7

0.967 (0.944-0.990)

.006

1.028 (0.998-1.059)

.06

AUDIT

0.985 (0.959-1.011)

.26

1.001 (0.973-1.030)

.95

Abnormal MDQ Score

0.573 (0.376-0.874)

.01

1.954 (1.286-2.970)

.002

Presence of Low Back Condition

0.815 (0.581-1.145)

.24

1.559 (1.065-2.282)

.02

a Remission and persistent depressive symptoms were defined as Patient Health Questionnaire (PHQ-9) scores of <5 or ≥10, respectively, at 6 months after enrollment. We controlled for patient age, sex, marital status, and race, along with clinical site location, to control for site-to-site variability in outcomes.

Odds Ratio for Clinical Outcomes of Depression at 6 Months After Enrollment in Collaborative Care Management, by Variable (N=1326)

Depression Outcome at 6 moa

Remission

Persistent Depressive Symptoms

Variable

Odds Ratio (CI)

P Value

Odds Ratio (CI)

P Value

Depression Diagnosis

First Episode

Referent

Referent

Recurrent

0.667 (0.525-0.847)

.001

1.227 (0.918-1.640)

.17

Dysthymia

0.992 (0.602-1.636)

.98

1.355 (0.764-2.403)

.30

Initial Test Score

PHQ-9

0.940 (0.911-0.970)

<.001

1.101 (1.062-1.142)

<.001

GAD-7

0.967 (0.944-0.990)

.006

1.028 (0.998-1.059)

.06

AUDIT

0.985 (0.959-1.011)

.26

1.001 (0.973-1.030)

.95

Abnormal MDQ Score

0.573 (0.376-0.874)

.01

1.954 (1.286-2.970)

.002

Presence of Low Back Condition

0.815 (0.581-1.145)

.24

1.559 (1.065-2.282)

.02

a Remission and persistent depressive symptoms were defined as Patient Health Questionnaire (PHQ-9) scores of <5 or ≥10, respectively, at 6 months after enrollment. We controlled for patient age, sex, marital status, and race, along with clinical site location, to control for site-to-site variability in outcomes.

We examined the impact of temporally related LBCs (occurring within 3 months of diagnosis of depression and a PHQ-9 score of ≥10) on depression outcomes at 6 months. The clinical outcomes studied were remission (PHQ-9 score <5), persistent depressive symptoms (PHQ-9 score ≥10), and number of outpatient visits (outlier status, ≥80th percentile). Our hypothesis was correct for 2 of the 3 outcomes. The presence of an LBC did not affect remission negatively, but it was associated with both persistent depressive symptoms at 6 months and increased number of outpatient visits, even when we controlled for clinical outcomes, prior outpatient visit patterns, and baseline demographics.

Our findings may encourage clinicians to identify patients with depression who have LBCs and consider more aggressive management of both conditions. We recommend future research to determine whether effective management of LBCs affects depression outcomes, as well as research on specific, directed therapy for both diagnoses. Unfortunately, the small size of our LBC group did not allow for the analysis of subgroups. We also did not examine the effects of depression outcomes on LBC outcomes, but that would be an intriguing future area of study.

Our study did not differentiate between acute and chronic LBCs, but it is possible that many of the 172 individuals with evidence of LBCs had chronic low back pain. Chronic low back pain responds best to multimodal therapy, but pharmacologic treatment is common, whether alone or in combination with other modalities.39 In 1 study,40 approximately 80% of patients with chronic low back pain were prescribed at least 1 medication and 34% were prescribed at least 2. Some of these medications are also used to treat patients with depression. A 2010 study41 demonstrated central sensitization as the common pathophysiologic mechanism for both chronic low back pain and depression. Duloxetine, with its unique indications for chronic pain and depression therapy, has demonstrated statistically significantly reduced Brief Pain Inventory scores in randomized double-blind trials (P<.01), making duloxetine suitable for patients with chronic low back pain and depression.42,43

The present study supports the major osteopathic principle that a person is an integrated unit of body, mind, and spirit, demonstrating the persistent association of a common psychiatric illness (depression) with a common physical condition (LBC). Reinforcing this association, a 2012 study21 correlated depression scores with low back pain severity, back-specific disability, and the number of key osteopathic lesions. A multimodal approach to osteopathic treatment of patients with depression and LBCs should strongly be considered by osteopathic physicians who are adequately trained.

Our study had several limitations. First, our patients were from a single clinical group practice with little diversity in insurance coverage and other demographic variables, such as race; this may limit the generalizability of the results to other clinical sites. Second, because our study included patients who entered the CCM database after receiving a diagnosis of depression, there was no control group of patients with depression and LBCs receiving usual care. In addition, our EMR search did not include patients who chose to use only chiropractic or other therapies (eg, massage, acupuncture) for low back pain. Third, because the study was retrospective, there may be confounding variables that were not studied. For example, catastrophizing, defined as distorted thought magnification of the pain and a common target in the management of many psychological disorders, would be an important variable to assess as an independent predictor of treatment outcome because of its association with persistence of pain.44,45 Finally, we did not look at other comorbid conditions that may also increase the number of outpatient visits and negatively affect depression outcome, such as heart disease, diabetes mellitus, and chronic obstructive pulmonary disease.46

The current study was a baseline investigation that supports the importance of additional inquiry into the effects of LBCs on CCM outcomes. For more specific results, future studies might analyze group differences by comparing, for example, chronic vs acute back pain, different levels of severity of back pain, the presence vs absence of radiographic abnormalities or obesity, personality traits such as introversion vs extraversion, and somatic distress vs minimizing-type behavioral expression. Because many components of CCM are not yet used in regular outpatient practice, future care systems, such as accountable care organizations, may incorporate new models such as CCM. Management of complex, multiple comorbid disease processes, as seen in our study, may help with the transformation.

Conclusion

In comparing patients with or without concomitant LBCs, we demonstrated increased odds of persistent depressive symptoms and increased number of outpatient visits 6 months after enrollment into CCM for those with LBCs. Future work is recommended, including directed therapy for patients with both depression and LBCs.

Acknowledgment

Isaac Johnson, MBA, and Julie Maxson, BA, assisted with abstraction and collection of the data.

Financial Disclosures: None reported.

Support: This study was funded by the Mayo Clinic Department of Family Medicine.

Chou R, Huffman LH. Medications for acute and chronic low back pain: a review of the evidence for an American Pain Society/American College of Physicians clinical practice guideline. Ann Intern Med. 2007;147(7):505-514.
[CrossRef][PubMed]

Odds Ratio for Clinical Outcomes of Depression at 6 Months After Enrollment in Collaborative Care Management, by Variable (N=1326)

Depression Outcome at 6 moa

Remission

Persistent Depressive Symptoms

Variable

Odds Ratio (CI)

P Value

Odds Ratio (CI)

P Value

Depression Diagnosis

First Episode

Referent

Referent

Recurrent

0.667 (0.525-0.847)

.001

1.227 (0.918-1.640)

.17

Dysthymia

0.992 (0.602-1.636)

.98

1.355 (0.764-2.403)

.30

Initial Test Score

PHQ-9

0.940 (0.911-0.970)

<.001

1.101 (1.062-1.142)

<.001

GAD-7

0.967 (0.944-0.990)

.006

1.028 (0.998-1.059)

.06

AUDIT

0.985 (0.959-1.011)

.26

1.001 (0.973-1.030)

.95

Abnormal MDQ Score

0.573 (0.376-0.874)

.01

1.954 (1.286-2.970)

.002

Presence of Low Back Condition

0.815 (0.581-1.145)

.24

1.559 (1.065-2.282)

.02

a Remission and persistent depressive symptoms were defined as Patient Health Questionnaire (PHQ-9) scores of <5 or ≥10, respectively, at 6 months after enrollment. We controlled for patient age, sex, marital status, and race, along with clinical site location, to control for site-to-site variability in outcomes.

Odds Ratio for Clinical Outcomes of Depression at 6 Months After Enrollment in Collaborative Care Management, by Variable (N=1326)

Depression Outcome at 6 moa

Remission

Persistent Depressive Symptoms

Variable

Odds Ratio (CI)

P Value

Odds Ratio (CI)

P Value

Depression Diagnosis

First Episode

Referent

Referent

Recurrent

0.667 (0.525-0.847)

.001

1.227 (0.918-1.640)

.17

Dysthymia

0.992 (0.602-1.636)

.98

1.355 (0.764-2.403)

.30

Initial Test Score

PHQ-9

0.940 (0.911-0.970)

<.001

1.101 (1.062-1.142)

<.001

GAD-7

0.967 (0.944-0.990)

.006

1.028 (0.998-1.059)

.06

AUDIT

0.985 (0.959-1.011)

.26

1.001 (0.973-1.030)

.95

Abnormal MDQ Score

0.573 (0.376-0.874)

.01

1.954 (1.286-2.970)

.002

Presence of Low Back Condition

0.815 (0.581-1.145)

.24

1.559 (1.065-2.282)

.02

a Remission and persistent depressive symptoms were defined as Patient Health Questionnaire (PHQ-9) scores of <5 or ≥10, respectively, at 6 months after enrollment. We controlled for patient age, sex, marital status, and race, along with clinical site location, to control for site-to-site variability in outcomes.